The subject matter disclosed herein relates to relates to a multi-layer radiation detector configuration, with each layer providing different information regarding the incident radiation.
Non-invasive imaging technologies allow images of the internal structures or features of a patient to be obtained without performing an invasive procedure on the patient. In particular, such non-invasive imaging technologies rely on various physical principles, such as the differential transmission of X-rays through the target volume or the reflection of acoustic waves, to acquire data and to construct images or otherwise represent the observed internal features of the patient.
For example, in computed tomography (CT) and other X-ray based imaging technologies, X-ray radiation spans a subject of interest, such as a human patient, and a portion of the radiation impacts a detector where the image data is collected. In digital X-ray systems a photo detector produces signals representative of the amount or intensity of radiation impacting discrete pixel regions of a detector surface. The signals may then be processed to generate an image that may be displayed for review. In CT systems a detector array, including a series of detector elements, produces similar signals through various positions as a gantry is displaced around a patient.
In the images produced by such systems, the internal structures and organs within a patient's body may be identified and their structure examined. It may also be desirable to characterize the tissues or agents that are present in the imaged volume, such as based on tissue type or the presence or absence of a chemical or molecule of interest, such as a contrast agent. However, in practice, such characterization may be difficult to achieve. In particular, in conventional computed tomography (CT), the X-ray attenuation proximity of multiple tissues at any given energy may make tissue classification difficult to achieve. That is, although materials have a distinct attenuation profile across different energies, tissue separation is not trivial as tissues are a mixture of different materials with range of densities and atomic number that vary across subjects.
Based on these difficulties, various approaches have been attempted for improving such tissue or chemical characterization within acquired images. Examples of such techniques often utilize X-ray emission at multiple, different spectra, such as two spectra with one spectrum characterized as a high energy relative to the other, low energy spectrum. However, in practice, such multi-spectral imaging approaches are still inadequate at providing good energy discrimination, thus limiting the applicability and usefulness of these approaches.